Electronic elements (such as resistance, capacitance, and so on) of a flexible printed circuit board are embedded into the flexible printed circuit board, so that a thickness of the flexible printed circuit board is reduced, as well as reducing a thickness of an electronic product having the flexible printed circuit board.
In traditional manufacturing processes, a multilayer circuit board is provided with open holes defined therein, and the electronic elements are received in the open-holes. However, due to the difference in height of different electronic elements, it is difficult to ensure that pads of the electronic elements have the same height to a copper layer on the surface of the embedded substrate, thereby causing different depths of the holes to be opened when the electronic elements are connected. In the production process, the processing depth of each hole is different, which greatly affects the working efficiency, and affects connection effect between the electronic elements and the circuit pattern.
Therefore, there is room for improvement within the art.